A personal assistant program provides services traditionally provided by a human assistant. For example, a personal assistant can update a calendar, provide reminders, track activities, shop for the user, and perform other functions. Some personal assistant programs can respond to voice commands and audibly communicate with users. Personal assistants can suggest restaurants, music, tasks, movies, and other items to a user when the user might have an interest in one of these items. Personal assistants can analyze signal data to determine a user's current context.